cannot load gridscan from queue if axis has units none

[ddkohler]

Caused the by our recent updates to bluesky versions:

Traceback (most recent call last):
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\queue.py", line 429, in load
    self.on_load_item(item)
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\queue.py", line 335, in on_load_item
    self.plan_widgets[item["name"]].args = item.get("args", [])
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\plan_ui.py", line 104, in args
    item.args = args
    ^^^^^^^^^
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\plan_ui.py", line 513, in args
    self.add_axis(*c)
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\plan_ui.py", line 620, in add_axis
    axis = GridscanAxis(hardware, start, stop, npts, units)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\somatic\plan_ui.py", line 584, in __init__
    self.add("Units", self.units)
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\project\widgets.py", line 143, in add
    getattr(self, global_type)(name, global_object)
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\project\widgets.py", line 316, in combo
    global_object.give_control(control)
  File "C:\Users\Thor_WISC\source\bluesky-cmds\bluesky_cmds\project\classes.py", line 202, in give_control
    self.widget.setCurrentIndex(allowed_values_strings.index(str(self.read())))
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: 'None' is not in list

[ddkohler]

Okay, not a bluesky issue; traceback makes it clear that it wasn't expecting a daemon with no units (in this case, the ND wheel is working with units of steps). We can help blueskky-cmds handle units of none, or alternatively, we can give the ND wheel units